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Development Of Deficient Grout And Corrosion In Post-Tensioned Tendons Due To Water And Solute Transport

Bridge construction utilizing post-tensioned (PT) tendon systems have become increasingly popular. 1-2 PT construction allows engineers greater options for the design of highway bridges and provides efficient structures with advantages in construction, economy, and serviceability. In bonded post stresses to the reinfotensioned systems, the introduction of rced concrete element is made through tensioned highstrength steel strand that are anchored and encapsulated in a cementitious grout within a tendon.3-4 The hardened grout allows development of the stress along the length of the tendon and also provides corrosion protection by the presence of the alkaline pore water to passivate the steel strand and by creating a barrier from external contaminants.

Product Number: 51322-17986-SG
Author: Rutambara Sonawane, Samanbar Permeh, Kingsley Lau
Publication Date: 2022
Industry: Highways & Bridges
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$20.00
$20.00

PT construction provides efficient bridge with advantages in construction, economy, and serviceability. In bonded posttensioned systems, the introduction of stresses to the reinforced concrete element is made through tensioned highstrength steel strand t hat are encapsulated in a cementitious grout. The hardened grout provides corrosion protection by the presence of the alkaline pore water to passivate the steel strand and by creating a barrier from external contaminants. However, there have been documente d cases of strand corrosion relating to deficiencies of the grout materials. Segregation of thixotropic grouts allowed for the development of chemically deficient grouts (characterized as having high sulfate concentrations) in verticallydeviated tendons in part attributed to an upward moisture and ion mobility. The Schupak pressure bleed test and vertically cast grout specimens was utilized to assess the performance of grout materials subjected to adverse construction practices including prehydration and a ddition of excess mix water. Results indicated that there is limited availability of sulfate ions upon initial grout casting but would still be able to accumulate via transport of the free water. Greater pressures and vertical deviations allowed for greate r accumulation. moisture transport and sulfate Keywords, PT tendons, grout, segregation, sulfate, bleed INTRODUCTION Bridge construction utilizing post increasingly popular. 12tensioned (PT) tendon systems have become PT construction allows engineers greater options for the design of highway bridges and provides efficient structures with advantages in construction, economy, and serviceability. 

PT construction provides efficient bridge with advantages in construction, economy, and serviceability. In bonded posttensioned systems, the introduction of stresses to the reinforced concrete element is made through tensioned highstrength steel strand t hat are encapsulated in a cementitious grout. The hardened grout provides corrosion protection by the presence of the alkaline pore water to passivate the steel strand and by creating a barrier from external contaminants. However, there have been documente d cases of strand corrosion relating to deficiencies of the grout materials. Segregation of thixotropic grouts allowed for the development of chemically deficient grouts (characterized as having high sulfate concentrations) in verticallydeviated tendons in part attributed to an upward moisture and ion mobility. The Schupak pressure bleed test and vertically cast grout specimens was utilized to assess the performance of grout materials subjected to adverse construction practices including prehydration and a ddition of excess mix water. Results indicated that there is limited availability of sulfate ions upon initial grout casting but would still be able to accumulate via transport of the free water. Greater pressures and vertical deviations allowed for greate r accumulation. moisture transport and sulfate Keywords, PT tendons, grout, segregation, sulfate, bleed INTRODUCTION Bridge construction utilizing post increasingly popular. 12tensioned (PT) tendon systems have become PT construction allows engineers greater options for the design of highway bridges and provides efficient structures with advantages in construction, economy, and serviceability. 

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